JNCIS-ENT: Juniper Networks Certified Specialist – Enterprise Routing and Switching (2025) — Question 28

Each PC and IP phone in your network is connected to a switch using the same port. All incoming data traffic is untagged and belongs to the v10 VLAN, while traffic coming from the IP phones is tagged with a VLAN value of 20 and should belong to the v20 VLAN on your switch.
In this scenario, which statement is correct?

Answer options

• A. You must enable the voice VLAN feature on the incoming interfaces and assign the v20 VLAN.
• B. You must enable an IRB interface and assign it to the v10 and v20 VLANs.
• C. You must enable LLDP-MED on the incoming interfaces and assign the v20 VLAN.
• D. You must enable the guest VLAN feature on the incoming interfaces and assign the v20 VLAN.

Correct answer: C

Explanation

The correct answer is C because enabling LLDP-MED allows the switch to identify and properly configure the voice VLAN for IP phones, which need to be tagged with v20. Option A is incorrect as voice VLAN is needed, but LLDP-MED is the method to apply it. Option B is wrong since IRB interfaces are not required in this scenario. Option D is also incorrect because guest VLANs are unrelated to the specific use case of IP phones requiring a voice VLAN.